We propose to examine how stressful situations affect biochemical processes that in turn have important effects on behavior. The biochemical processes we will study involve brain monoamines because monoamines are implicated in abnormal behavior, particularly depression and schizophrenia. Previous research in our laboratory and others has found that animals receiving inescapable shock show changes in brain norepinephrine as well as deficits in active motor behavior, whereas animals that received the same shocks in the course of performing an effective coping response do not show these brain norepinephrine changes and are not behaviorally impaired. The objective of this research is to specify more precisely how inescapable shock affects monoamines so as to depress active avoidance-escape responding and motor activity. We study how inescapable shock affects monoamines, studying how it alters monoamine level, uptake, and receptor sensitivity. Shock-induced changes in levels of the three monoamines are followed over time after the stress session and these changes are correlated with changes in avoidance-escape behavior. We then study changes in uptake, which are likely to have significant effects on behavior since uptake influences the amount of receptor stimulation. Uptake of dopamine and serotonin particularly are examined. Finally, possible effects of inescapable shock on receptor sensitivity are explored.